Respirators are commonly worn over the breathing passages of a person to prevent impurities or contaminants from entering the wearer's respiratory tract.
A variety of respirators have been designed to meet this purpose. Some military respirators have been categorized as Joint Service General Purpose Masks (“JSGPM's”), for which filters will need to be periodically replaced to remain useful.
The effectiveness of JSGPM has been evaluated by comparing the amount of corn oil aerosol in a test chamber to that inside the mask while the test subject performs various exercises designed to stress the seal of the mask while wearing the mask in the chamber. Higher protection factor values assigned to the mask indicate that the user is getting a good seal and there is little or no contamination inside the mask.
Some of these aerosol tests were conducted as filter exchange tests to ensure that a user can switch out filters in a contaminated environment. During these trials, a user removes a filter on one side of the mask, relaxes for one minute to ensure that a seal is maintained, and then replaces the filter. The test results are evaluated on whether the protection factor value during the filter removal exercise goes below a certain threshold. The JSGPM performs well in this regard. However, when the filter is replaced on the mask, the contamination that is trapped in the cavities between the JSGPM filter mount and the filter canister itself can be pushed up into the mask by air pressure. This air movement reduces the Protection Factor of the mask from anywhere between 50-100 PF, which indicates that for several seconds the user is breathing a large amount of contamination from outside of the mask. While it is not hazardous to breathe in corn oil during a filter replacement test, in a real contaminated environment such a contamination spike would be enough to incapacitate or even kill a user based on the chemical or biological agent that was inhaled. This concern deters an individual user in the field from replacing filters in a contaminated environment, and users must exit the area of contamination to replace fitters and then re-enter the contaminated location to continue the mission, which greatly reduces the mission effectiveness.
A new filter connection system is being provided herein to address this issue. Various designs of the filter connection system will focus on removing the air cavities between the filter mount and filter canister, so that when users replace a filter while wearing a mask in a contaminated environment, the spike of contamination can be eliminated or greatly reduced.